Don't format error messages on validators

[nryoung]

In refs to: #3354

This removes .format calls on error messages and defaults to using the default class attribute error message.

[tomchristie]

Couple of things here:

1. This doesn't appear to remove it everywhere, eg CharField?
2. I think we'd still want to pass the message through. (So they can be specified at the field class level)

[nryoung]

1. This doesn't appear to remove it everywhere, eg CharField?

Good catch, however, when I remove this from the CharField it seems that self.message is not assigned? I am not entirely sure what ungettext_lazy is doing on the MaxLengthValidator: https://github.com/django/django/blob/stable/1.7.x/django/core/validators.py#L284-L287

1. I think we'd still want to pass the message through. (So they can be specified at the field class level)

Do you mean something along the lines of?:

self.validators.append(MaxLengthValidator(self.max_length, message=self.message))

[tomchristie]

Do you mean something along the lines of

That's what I was thinking - tho let's look to Django's Field classes for direction.

[nryoung]

let's look to Django's Field classes for direction.

Looking at both Django's IntergerField and CharField, only the value is passed in to the validator: https://github.com/django/django/blob/master/django/db/models/fields/__init__.py#L1881, https://github.com/django/django/blob/master/django/db/models/fields/__init__.py#L1094

[nryoung]

OK @tomchristie, I followed Django's Field classes here and made changes accordingly. message is not passed in to the validator on initialization.

[xordoquy]

@nryoung I'm not sure your last commit what was we had in mind.
It breaks the current error message customization scheme. Error messages for min/max will now be within the MaxLengthValidator/MinLengthValidator instead of CharField.
This might break anyone that tuned its error message.

Can't we instead simply pass the unformatted message to the Validator and be using the Validation's formatters instead of the current format ?

[xordoquy]

ie:

    default_error_messages = {
        ...
        'max_length': _('Ensure this field has no more than {max_length} characters.'),
        ...
    }

would become:

    default_error_messages = {
        ...
        'max_length': ungettext_lazy(
            'Ensure this value has at most %(limit_value)d character (it has %(show_value)d).',
            'Ensure this value has at most %(limit_value)d characters (it has %(show_value)d).',
            'limit_value')
        ...
    }

[nryoung]

@xordoquy understood. I misunderstood what @tomchristie was asking for. I can probably get this fixed up tomorrow.

[tomchristie]

@xordoquy @nryoung That's a separate issue, no?

[xordoquy]

@tomchristie I don't think so. In my snippet it should defer the format to the moment the validation is performed which should fix the initial issue.

[tomchristie]

Okay, so how would you rephrase it without bringing in the (unrelated) pluralization issue.

The problem is that the lazy translation is being evaluated at the point that we format it, no?

[xordoquy]

@tomchristie it's a bit more complex than it appears. Will open a new PR a bit later.

[tomchristie]

Closing this off as stale.